DESCRIPTION (provided by investigator): Bulimia Nervosa (BN) is a serious eating disorder characterized by frequent uncontrolled eating binges. Binge Eating Disorder (BED) is a more recently described disorder which occurs primarily in obese individuals and which is associated with significant morbidity. While much is known about the characteristics and treatment of these disorders, particularly BN, there is as yet a limited understanding of their pathophysiology. The aim of this ongoing research program is to describe objectively the eating behavior of individuals with disorders of binge eating and, using this information, to generate and test hypotheses concerning their pathophysiology. Work to date has focused on the inhibitory controls of eating, i.e., the development of satiety during a meal, and considerable evidence has been obtained suggesting that binge eating in BN and BED reflects a disturbance in these controls. Studies of gastrointestinal function in BN demonstrated abnormalities in gastric emptying, postprandial gastric relaxation, and cholecystokinin (CCK) release, and suggested a physiological model of altered satiety in BN. Other findings suggested a disturbance in the excitatory controls of eating in BN and BED. The proposed project will critically test, both in the laboratory and the clinic, the hypothesis that disturbances in the inhibitory and excitatory controls of eating contribute to behavioral symptoms in BN and BED. Experiments in patients with BN will determine whether the administration of CCK reduces binge eating in a laboratory setting, and whether treatment with erythromycin, an agent that accelerates gastric emptying, enhances CCK release and reduces the frequency of binge eating. Other experiments focusing on BN will determine whether an increased rate of eating is necessary to produce the increased caloric intake characteristic of binge eating. Experiments focusing on BED will determine whether individuals with this disorder have disturbances in the release of CCK and in gastric emptying similar to those of individuals with BN. Additional experiments will examine whether excitatory controls of eating, as reflected by sham feeding (i.e., consumption of non-caloric food) and by cue reactivity, are increased in patients with BN and BED.